The present invention relates to a cyclone which constitutes a part of a suspension preheater used as a preheating device for heating materials in a cement producing apparatus, and to other general cyclones, and also relates to a straightening instrument used in a fine particle discharge section of a swirl flow type classifier and to a cyclone using such a straightening instrument.
Heretofore, in a cyclone using the above-mentioned type straightening instrument, wherein a multiphase stream containing a powder or granule material and a fluid is introduced tangentially into a swirl cylinder through its upper opening, and then the powder or fine particle material is separated within the swirl cylinder while thus separated powder or fine particle material being lowered in the cylindrical casing so as to be discharge though its lower discharge opening, and wherein a fluid including in part a fine powder is discharged to a next process station through a fluid discharge inner tube which is attached to the center of the upper end section of the cylindrical casing and which is opened to the inside of the cylindrical casing, a plurality of rectifying vanes which are twisted blades having an arbitrary blade width that is smaller than one-half of the inner diameter of the above-mentioned fine particle discharge inner tube, are attached in one and the same inner peripheral surface of the inner tube at an arbitrary position so that it can be moved by a suitable drive means in the axial direction of the discharge cylinder, thereby the swirl stream in the inner peripheral direction is turned into an axial stream (Refer to Japanese Laid-Open Patent No. 52-149666).
The above-mentioned cyclone with rectifying vanes attached to the forward end of the inner tube can reduce a pressure loss relatively, in comparison with a cyclone having no such rectifying blades attached to the inner tube. However, a lowering of collecting efficiency is inevitable in this cyclone. On the contrary, should the collecting efficiency be maintained, a reduction in collecting efficiency is not always satisfactory (refer to Japanese Laid-Open Patent No. 52-149666).
One object of the present invention is to reduce the pressure loss in the above-mentioned conventional device by an extremely large degree without lowering the collecting efficiency thereof.